Fuel efficiency decreases for vehicles undergoing an engine cold-start due to increased friction of movable parts, increased viscosity of engine oil, and an exhaust aftertreatment device not being lit-off. For the above-mentioned reasons, endeavors in the further development of internal combustion engines are focused on achieving quicker heating of the exhaust aftertreatment device. Furthermore, engines are operated within a certain temperature range and in order to operate with the range, a coolant system may be used. Air-cooled internal combustion engines for this purpose have areas comprising a usually fin-like external structure in order to deliver some of the operating heat to the surrounding air via the surface thus enlarged. By contrast, the coolant rinsing over the engine block and the cylinder head in the case of water-cooled internal combustion engines absorbs a large part of the waste heat produced. For this purpose, channels usually arranged in the housing wall of the internal combustion engine are provided and together with the coolant flowing therethrough form what is known as a coolant jacket.
In order to prevent an overheating of the coolant, this is then conveyed via a closed cooling circuit through a suitable cooler. Here, at least some of the heat absorbed by the coolant is delivered to the surrounding air via the cooler, which is usually formed as a gas-coolant heat exchanger.
Since the introduction of water cooling, it has been known to combine engine cooling systems of this type with a vehicle heating system. In this way, the heat from the coolant produced can also be used to heat the vehicle interior (e.g., passenger cabin) independently of external influences. A heat exchanger routinely formed as a gas-coolant heat exchanger may be integrated into the cooling circuit. The operation of the vehicle heating system ensures that air from outside or from the interior of the vehicle is sucked in and guided past the heat exchanger or therethrough. In doing so, the air absorbs some of the heat energy before it is conveyed into the interior of the vehicle.
Besides the resultant increased comfort, however, vehicle heating systems also perform other desired operations, such as defrosting windows. By way of example, low external temperatures cause steam in the interior to precipitate onto the windowpanes. As a result, these may then become misted or even iced, whereby the view is clouded or even completely prevented. The defrosting ability of the vehicle heating system may aid in decreasing the precipitate accumulated onto the windowpanes.
Various embodiments of engine cooling systems in combination with vehicle heating systems may already be known. These in part provide a flow-free strategy, which is also referred to as a “no-flow strategy”. The circulation of the coolant through the coolant jacket of the internal combustion engine is interrupted, in particular during the cold-start phase to allow the engine to reach an optimal operating temperature more rapidly. However, strategies of this type are not always suitable for vehicle heating systems operated with coolant. For example, an operator of the vehicle may desire interior vehicle heating during a cold-start due to low ambient temperatures, which in turn initiates coolant to flow to the engine, thus disabling the no-flow strategy.
In order to be able to apply the no-flow strategy in conjunction with a vehicle heating system using coolant flow, split cooling systems have been established. These provide a separation of a cooling circuit, the coolant jacket of the internal combustion engine being divided into a part for the engine block and into a part for the cylinder head. It is possible in this way to apply flowing coolant to the coolant jacket of the cylinder head directly from the start-up of the internal combustion engine, whereas the coolant flow to the coolant jacket of the engine block is advantageously still blocked (no-flow strategy).
Since the cylinder head containing the outlets for the exhaust gas experiences the greatest heating, the part of the coolant heated via this cylinder head can be used for the vehicle heating system. By contrast, the blocked part of the coolant jacket contributes to the fact that the engine block can be heated more quickly, without losing the heat energy required for this purpose in parts to the otherwise flowing coolant.
In particular, previous split cooling systems provide a division of the coolant jacket provide the arrangement of a proportional valve in order to control the individual parts of the cooling circuit. Here, a mixing of the coolant is prevented in that the sub-circuits are structurally separate from one another. Consequently, only the sub-circuit acting on the cylinder head is available in order to supply the vehicle heating system as required. This sometimes may be insufficient in the event of a high heat request for the heating of the vehicle interior. At the same time, the cooling of the internal combustion engine via the cooler is limited to the sub-circuit acting on the engine block. This leads to a reduced cooling capability of the internal combustion engine, since the entire coolant flow guided through the engine is not conveyed to the cooler.
As a result, neither a maximum cooling of the internal combustion engine nor a maximum heating of the vehicle interior consequently may be achieved. A possible balancing of these shortcomings via more efficient and/or larger coolers or a growing size of the coolant pump makes such systems more costly and does not always lead to the desired success.
CA 2 405 444 A1 discloses another form of a split cooling system for an internal combustion engine equipped with a turbocharger. However, the internal combustion engine here has a single coolant jacket passing through both the engine block and the cylinder head jointly. In addition, a liquid-cooled oil cooler is additionally provided, which is fluidically connected to the coolant jacket and a cooler as well as a liquid-cooled intercooler for the turbocharger and a coolant pump via a cooling circuit. A control means in the form of a multiple-way valve is arranged within the cooling circuit and controls the passage of the coolant to the individual components. The control means has a housing with a rotary body arranged therein, the rotary body being rotatable about its longitudinal axis. Parts of the rotary body communicate with outlets arranged on the housing around the longitudinal axis, in such a way that these are at least partially closed or opened depending on the position of the rotary body. The coolant flow can thus be split as required between parts of the cooling circuit and the components arranged therein.
In one example, the issues described above may be addressed by a method for rotating a rotating body of a control means of a split cooling system to one of a plurality of rotation positions based conditions to direct coolant flow from an upper side of a cylinder head and from a crankcase to one or more of a main coolant circuit, a secondary coolant circuit, and an external bypass, and where coolant from the upper side mixes with coolant from the crankcase for some of the rotation positions. In this way, coolant may be directed to a plurality of passages via a single device
As one example, the valve may be rotated to a position such that coolant from the upper side may mix with coolant from the crankcase to provide increased cooling of the engine. In another example, the valve may be rotated to a different position such that coolant from the upper side may mix with coolant from the crankcase to provide increased vehicle heating. By doing this, one valve may be used to adjust engine cooling, vehicle heating, and/or engine heating. The split cooling system may simultaneously heat the engine while providing vehicle heating for one position of the valve. This may decrease manufacturing costs of the split cooling system while also decreasing a size of the cooling system.
It should be noted that the features discussed individually in the following description can be combined with one another in any technically feasible manner and therefore present further embodiments of the present disclosure. The description characterizes and specifies the present disclosure additionally in particular in conjunction with the figures. It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.